The state of the immune system in dogs before and after deworming and methods of its correction were analyzed in this paper. The monitoring studies were shown that in a metropolis of large cities (Kyiv, Lviv), the degree of infestation by helminths in dogs observed at 36.7 and 37.9%. Thenamatodozy and cestodosis were prevailing over this disease. The infestation oftoxocara in dogs of different breeds was 24.4-34.6%, dippilidiyami - 17.4-24.2%, toksaskarisami - 4.8-7.2%, teniyami - 3,6 5,2% hookworm - 1.0-1.3%, echinococcus 0.25-0.3%. The obtain data have shown that the parameters of the immune status of dogs before and after prophylactic deworming are characterized by significant changes. For example, in dogs, before the antiparasitic treatment, the number of white blood cells and the level of seromucoid increased in the blood and the number of T- and B-lymphocytes, phagocytic activity of neutrophils, bactericidal and lysozyme activity reduced in blood serum. Inhibition of humoral and cellular immunity is probably the result of a chronic or latent form of helminthic diseases, which requires not only antiparasitic activities but also immunologic correction. It was shown that after deworming the studied parameters are different from the indices for clinically healthy dogs, which is the result of the immunosuppressive action of worms and especially their toxins. A similar effect can be observed for "Brovanol D". Use of dietary supplement "Silimask", which consists of crushed fruits of milk thistle, bee pollen, ascorbic acid and antioxidant "Metifen" for the correction of immune status in dogs promoted a recovery of indexes characteristic of clinically healthy dogs on the 30th day of its application